In matrix printing, the wire matrix employed in forming each alpha-numeric character is defined by a predetermined number of impressions arranged in a column which may be vertical or inclined and which are advanced to a predetermined number of laterally spaced positions. For example, a 5 .times. 7 matrix is comprised of seven print members each capable of printing a dot in the column in each of five parallel columns, thereby forming a legible, alpha-numeric character.
In the past, providing channels for the print members having low resistance paths has been difficult because of the technique used in forming a low resistance path during the fabrication of the body containing the channels. A typical method of forming the body is to insert each of the print elements into a flexible tube and to support both ends of the wire as desired, that is, at the activation end and at the impression end. The wire then takes a natural, flexed position so that a potting compound can then be used to form the body and to fix the flexible tubes into the positions of paths that are of least resistance. The problem with this form of structure is that fabrication is a difficult assembly process and the handling of the mechanism during fabrication tends to upset the curvature of the path, thereby resulting in a path with too much resistance.
This invention permits the manufacture of a printhead body by a simple molding process, such as injection molding. The printhead body may be formed of a moldable or castable material, such as, for example, thermoplastic or thermal setting material. The mold contains the impressions of the channels, the impressions having been formed in accordance with equations mathematically setting out the paths of least resistance.